The present invention relates to a vibrating piece formed of crystal or the like, a vibrator having the vibrating piece, and an oscillator or electronic equipment having the vibrator.
Generally, tuning-fork type crystal vibrating pieces which are vibrating pieces have a base and two arms formed in a manner protruding from the base, with grooves formed on the front of each of the two arms. The grooves are formed in the same way on the back of the arms as well. Accordingly, the arms have a generally H-shaped cross-sectional form.
Such generally H-shaped tuning-fork type crystal vibrating pieces have properties wherein vibration loss at the arms is low even when the size of the vibrating piece is miniaturized, and the CI value (crystal impedance or equivalent series resistance) can also be suppressed to a low level.
Accordingly, generally H-shaped tuning-fork type crystal vibrating pieces are applied to, for example, vibrators wherein precise performance is required even when miniaturized.
As for the size of a generally H-shaped tuning-fork type crystal vibrating piece, the length of the arms is 1.644 mm, the width is 0.1 mm, and grooves of 0.07 mm in width are formed on the arms. Further, the length of the base in the lengthwise direction is 0.7 mm.
Even with such extremely small tuning-fork type crystal vibrating pieces, further miniaturization is required to handle the demand for miniaturization of recent devices such as electric equipment or the like.
In order to handle the demand for such miniaturization, forming the lengthwise direction at the base so as to be shorter than 0.7 mm causes the overall length of the vibrating piece to be shorter, so the vibrating piece is miniaturized, which is best, but this has caused the following problems.
That is, generally, in the event that the length of the base is not made to be 40% or more of the length of the arms, there is the problem that effects due to fixing irregularities of the vibrating piece are readily manifested, and irregularities in CI values between vibrating piece devices readily occurs.
Specifically, in the event that the thickness of the arms is D, the width of the arms is W, and the length of the arms is L, the frequency f of the tuning-fork type crystal vibrating piece must satisfy the relational expression of
fxe2x88x9dW/L2 
That is, the relation is such that the short that the length L of the arms of the vibrating piece is, the narrower the width W of the arms is.
However, making the width W shorter as described above causes the vertical component of the vibration of the arms to increase, and in the event that the arms move the vibrations thereof are transmitted to the base of the vibrating piece, and energy escapes from the adhesive agent or the like at the fixing area of the base for fixing the vibrating piece to the package or the like.
Accordingly, in the event that vibrations leak to the base and energy escapes from the fixing area of the base, the vibrations of the arms in some vibrating pieces become unstable due to the effects of fixing irregularities in the vibrating pieces, increasing irregularities in CI values between devices.
In order to prevent such leaking of vibrations of the arms and escaping of energy from the fixing area of the base, length of 40% or more of the length L of the arms had to be secured at the base, as described above. Accordingly, this has been a hindrance in miniaturizing vibrating pieces themselves.
It is an object of the present invention to provide a vibrating piece wherein irregularities in IC value between vibrating pieces can be stabilized even in the event that the base is made shorter, while the overall vibrating piece can be miniaturized as well.
According to the present invention, the following vibration pieces (1) through (6) are preferably provided.
(1) A vibrating piece comprising: a base; and vibrating arms formed protruding from the base; wherein a groove is formed on at least one of the front side and rear side of the vibrating arms, and wherein notches are formed in the base.
(2) A vibrating piece comprising: a base; and vibrating arms formed protruding from the base; wherein a groove is formed on at least one of the front side and rear side of the vibrating arms and notches are formed in the base, and wherein the vibrating arms are generally parallelepiped, the width of the arm portion which is the short side of the front side thereof being 50 xcexcm or longer but 150 xcexcm or shorter.
(3) A vibrating piece comprising: a base; and vibrating arms formed protruding from the base; wherein a groove is formed on both of the front side and rear side of the vibrating arms, and wherein the depth of a groove formed on either the front side or rear side is 30% or more of the thickness of the vibrating arm which is the full length thereof in the depth direction but less than 50% thereof.
(4) A vibrating piece comprising: a base; and vibrating arms formed protruding from the base; wherein a groove is formed on both of the front side and rear side of the vibrating arms, and wherein the depth of a groove formed on either the front side or rear side is 40% or more of the thickness of the vibrating arm which is the full length thereof in the depth direction but less than 50% thereof.
(5) A vibrating piece comprising: a base; and vibrating arms formed protruding from the base; wherein a groove is formed on both of the front side and rear side of the vibrating arms, and wherein the depth of a groove formed on either the front side or rear side is 30% or more of the thickness of the vibrating arm which is the full length thereof in the depth direction but less than 50% thereof, and wherein the groove width which is the short side of the opening of the groove is 40% or more of the width of arm of the vibrating arm.
(6) A vibrating piece comprising: a base; and vibrating arms formed protruding from the base; wherein a groove is formed on both of the front side and rear side of the vibrating arms, and wherein the depth of a groove formed on either the front side or rear side is 30% or more of the thickness of the vibrating arm which is the full length thereof in the depth direction but less than 50% thereof, and wherein the groove width which is the short side of the opening of the groove is 70% or more of the width of arm of the vibrating arm but less than 100% thereof.